applications - Prevent USB data transfer (when phone is in use) and being charged

I would like to know how to protect my data when I use public battery charger in public places. I know that if I do not unlock my screen when charging, my data is safe, but what if I would like to use my phone while connected to public charger?

I would like to know how or if it requires to have an app that can help me block data transfer via USB , even if I am using the phone.